Electron discharge device for microwaves



Jan. 15, 1957 Filed April 10, 1952 R. H. SVENSSON ELECTRON DISCHARGE DEVICE FOR MICROWAVES 2 Sheets-Sheet 1 Br Hwy finale/v5) Jan. 15, 1957 R. H. SVENSSON 2,777,969

ELECTRON DISCHARGE DEVICE FOR MICROWAVES Filed April 10, 1952 2 Sheets-Sheet 2 g I2 I 26 27' I4 22 u A 6 FIG. 3

INVENTOR. REGNAR HOLMFRID SVENSSON BY M1? M ATTORNEY United States Patent ELECTRON DISCHARGE DEVICE FOR MICROWAVES Regnar Holmfrid Svensson, Copenhagen, Denmark, as-

signor to Telefonaktiebolaget L M Ericsson, Stockholm, Sweden, a company of Sweden Application April 10, 1952, Serial No. 281,532

4 Claims. (Cl. 315-5) This invention relates to an electron discharge device for microwaves with a resonator totally in vacuum.

One object of the invention is to provide such an electron discharge devise making an improved coupling to a wave guide possible.

Another object of the invention is to provide an electron tube with a coupling device intended for coupling the electron tube to a Wave guide, which coupling device is in good contact with the resonator of the electron tube both thermally and electrically.

Another object of the invention is to provide an electron tube with a coupling device, which is constructed in order to form a portion of a wall of the Wave guide.

A further object of the invention is to provide an electron tube with a coupling device, which gives not only an improved coupling to a Wave guide but also an improved cooling of the resonator of the electron tube.

In one embodiment according to the invention there is intended to provide an electron tube with thermal tuning.

One electron tube made according to the invention and in the drawing shown as a reflex klystron has its cavity resonator fastened to one side of a plate, whereby there is an iris in the plate and in the corresponding portion of the cavity resonator. Through a disk seal the plate is led out through the hermetical envelope of the tube, and arranged in such a manner that the outer portion of the plate is forming a ringshaped or similar coupling device for the connection of the electron tube to a portion of a wall of a wave guide.

A preferred embodiment of an electron discharge device according to the invention is characterized by one of the walls of the cavity resonator for tuning purpose being formed as a flexible diaphragm and mechanically connected to the junction of two supports, the other ends of which have a fixed position in relation to the main portion of the cavity resonator, whereby one of the supports is arranged to be heated in order to alter its length and thereby the position of the diaphragm in relation 'to the main portion of the cavity resonator.

Other and further objects, features and advantages of the invention will be pointed out hereinafter and set forth in the appended claims forming part of the application.

In the accompanying drawing a preferred embodiment of the invention is shown by Way of illustration and not by way of limitation.

In the drawing:

Fig. l is an elevational sectional view of an electron discharge device in form of a reflex klystron according to the invention.

Fig. 2 is a fragmentary elevational view of Fig. 1 turned through an angle of 90, and

Fig. 3 is a sectional view taken on line 33 of Fig. 1.

The resonant circuit of the reflex klystron is formed as a cavity resonator 24, the top of which is soldered to a plate 34. For this purpose this plate is provided with anupwardly directed bulge 32, surrounding the upper ice portion of the cylindrical part of the resonator 24. In

mutually corresponding portions of the resonator 24 and the plate 34 rectangular holes 31, 30 respectively are cut out, which holes form an iris, where the high frequency energy will be taken out. The plate 34 is provided with a jag 35 going round the plate to which jag the hermetical envelope 17, for instance made of glass, of the reflex klystron is fastened by a disk seal. The outer portion of the plate 34 constitutes a ringshaped coupling device for the connection of the reflex klystron to a portion of a wall of a wave guide 39. This wall is provided with a hole 2 in which the upper portion of the reflex klystron is threaded in such a way that the plate 34 is mounted on the wave guide 39. The coupling of the klystron to the wave guide may be varied by turning the klystron round the axis of the plate 34.

At each end of the resonator 24, plates 25 and 33 respectively of insulating material are mounted, which plates support the electron gun and the reflector electrode 6 of the klystron respectively. The electron gun consists of a concave cathode element 28, which is indirectly heated by a heater 26, and a focussing electrode 29 located in front of the cathode element 28. The adjacent end portion of the resonator is concave towards the cathode 28 and constitutes another focussing device 27 for the electron beam. The opposite wall of the cavity resonator is formed as a flexible diaphragm 11 with an opening 38 in the middle of it. The opening of the diaphragm as well as the adjacent portion of the focussing device 27 are provided with grids 36. The end portion of the focussing device 27 has a particular, new shape being made with a widening opening portion 37 in order that the returning electrons may be able to pass back through the outer edge of the grid of said portion 27 in such a way that they are captured by the bottom of the widening portion 37.

Surrounding the opening 38 of the diaphragm 11 there is attached a cone-shaped cap 4 fixed to the diaphragm. The cap 4 is provided with lugs 5 at two diametrically opposed places of its periphery, which lugs together are forming a yoke, attached to the upper end of a support 12. The cavity resonator 24 is also afiixed to the branches 23 of a yoke. The middle portion of that yoke, which portion is joining the branches 23, is indicated by 13. A cylinder-shaped support 14 has one of its ends fixed to the middle portion 13. The upper part of the support 14 is formed as an extension lug and fixed to the upper portion of the support 12. The support 14 is intended to be heated by a heater 15, which is situated in the cylindrical portion of the support. When the heater 15 is heated the support 14 will also be heated, whereby its length will increase. As a result the support 12 is forced to move angularly round a fixed point 12' formed by the lower end of the support, being aflixed to the middle portion 13. The connecting point of the supports 12 and 14 will then according to Fig. 1 move to the left. This movement will be transmitted by the lug 5 to the reflector electrode 6 and the diaphragm 11. When the bottom end of the support 12, that is the fixed point about which support 12 is angularly displaced is situated in a plane as defined by the plane through the diaphragm, the force acting upon the diaphragm is directed substantially perpendicularly to the diaphragm. Movement of the diaphragm to the left decreases the distance between the two grids 36, whereby the capacitance between them will be increased. As a result the resonant frequency of the cavity resonator will be decreased. By changing the amount of the input power to the heater 15 it is possible to vary the frequency of the oscillations, which are generated by the reflex klystron. The input power of the heater 15 may be varied, e. g. by means of a conventional magnetic amplifier suitable for the purpose.

For certain applications it isdesirable to tune the frequency of. the reflex. klystron. automatically up and down within the tuning range. In order to make such an operation possible a contact spring device of known construction, in Fig. 1 shown as two contact springs 21' and 22, may be built in within the hermetical envelope of the klystron. This contact spring device will be actuated by some part, which is moved by the support 14, which is heated by the heater 15. Said contact spring device may be used to switch on or off circuits controlling the bendings of the diaphragm.

Because the temperature of a thermic tuning device asymptotically approaches those temperatures corresponding to maximum input and no input to the heater, it is necessary in order to get a fast tuning within the wanted range that the maximum length alteration of the heated support should be greater than the value corresponding to the wanted tuning range.

The electrodes of the'refiex klystron are shown in the figure as wires 19 connected to pins 1%, which are fused in into the base-plate of'the envelope 1'7 As an example of the advantageousdata l have obtained with the reflex klystron according to the invention the following may be said. At 5060 mc./s.v and an input of 7 w. I have obtained an output of 180 m.w. and tuning range of 700 mc./s., which iszan appreciable improvement in relation to other existing reflex klystrons of types to be compared with my type.

The invention has above been described in connection with a reflex k'lystron. But it is evident that the invention may be applied not. only to reflex klystrons but also to other micro Wave tubes containing a resonator totally enclosed in vacuum.

I claim:

'1. In an electron discharge device, a cavity resonator including a wall portion in form of a diaphragm and components coacting with the diaphragm, support means supporting said diaphragm, the said support means comprising two elongated support members joined at one end and secured to the diaphragm with their joined ends, the other ends of the support members being fixedly mounted relative to the components of the cavity resonator coacting with the diaphragm, one of said support members being disposed in a plane parallel to the plane of the diaphragm, and heating means for heating said parallel t support member to vary the length thereof thereby causing, a change in the position of the diaphragm relative to the components of the cavity resonator coacting therewith for the purpose of tuning the device.

2. An electron discharge device according to claim 1, where-in the non-treatable support member is mounted with its respective end at a fixed point situated approximately in the plane of the diaphragm, the said support member being angularly displacable in response to a variation in the length of said heatable support member.

3. An electron discharge device according to claim 1 and further comprising switch means including stationary contact means and movable contact means, the latter contact means being mounted for movement in unison with said diaphragm" for controlling said switch means by the movement of said diaphragm.

4. An electron discharge device according to claim l in which the said device is a reflex klystron and wherein the cavity resonator thereofcomprises a generally tubular focusing member, a reflector electrode facing the focusing member and disposed in axial alignment therewith, said diaphragm being transversely disposed between the focusing member and the reflector electrode and formed with a ccntric'orifice, a first grid supported at the end of the focusing member facing the diaphragm and a second grid fitted in said diaphragm orifice, the face end of the focusing member supporting the first grid being annularly recessed so as to widen the cross-sectional area of the focusing area at said end, the said first grid extending over said widened cross-sectional area of the focusing member for capturing at the bottom of said recess electrons returning through the marginal portion of said first grid.

References Cited in the file of this patent UNITED STATES PATENTS 2,167,201 Dallenbach July 25, 1939 2,400,743 Clilford -2 May 21, 1946 2,408,817 Snow Oct. 8, 1946 2,414,496 Varian et a1 Jan. 21, 1947 2,521,763 Tomlin Sept. 12, 1950 2,566,584 Shepherd Sept. 4, 1951 FOREIGN PATENTS 626,289 Great Britain July 13, 1949 

